Computation of Earnings Per Share (Detail) - Calculations Of Basic And Diluted Earnings Per Share (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Numerator:
Net income used for calculating basic and diluted earnings per common share	$ 183,766		$ 182,801		$ 165,903
Denominator:
Weighted average number of common shares used in the calculation of basic earnings per share	89,337	[1]	93,015	[1]	93,444	[1]
Common share equivalents associated with stock-based compensation plans	1,382	[1]	1,815	[1]	2,398	[1]
Shares used in the calculation of diluted earnings per share	90,719	[1]	94,830	[1]	95,842	[1]
Earnings per share:
Basic (in Dollars per share)	$ 2.06		$ 1.97		$ 1.78
Diluted (in Dollars per share)	$ 2.03		$ 1.93		$ 1.73

[1] The Company repurchased 5.9 million, 3.4 million, and 2.7 million shares of its Common Stock in 2014, 2013, and 2012, respectively.